The objective of this project are 1) to determine the effect of age at menarche on adolescent subfecundability and on subsequent birth intervals, 2) to assess the effect of age at menarche and first birth on the completion of adolescent growth and adult height and weight, and 3) to determine the effect of age at first birth and the length of the interval between menarche and first birth on infant mortality in rural Bangladesh. Specifically, this project will examine the association between menarcheal age and the waiting time to conception from marriage to first birth. In addition, the association between menarcheal age and the length of subsequent birth intervals will be examined. The independent effects of both age at menarche and the interval between menarche and first birth on adult height and weight will also be assessed. A longitudinal data set from Matlab, Bangladesh for over 1,000 women followed over a period of 13 years provides a unique opportunity to study these relationships. Data include 1) ages at menarche, marriage and childbirth observed prospectively in two surveys and in registration records; and 2) height and weight collected in an 18 month survey where measurements were collected monthly and a single round survey in 1989. Results will contribute to the understanding of menarche as a marker of reproductive capacity, and the health effects of early childbearing in developing countries. Findings will stimulate informed policies and programs aimed at the prevention and management of adolescent childbearing in developing countries, through a better understanding of the effects of early childbearing on maternal and child health in a chronically malnourished population.